Inflation, cold dark matter, and the central density problem

A problem with high central densities in dark halos has arisen in the context of LCDM cosmologies with scale-invariant initial power spectra. Although n=1 is often justified by appealing to the inflation scenario, inflationary models with mild deviations from scale-invariance are not uncommon and models with significant running of the spectral index are plausible. Even mild deviations from scale-invariance can be important because halo collapse times and densities depend on the relative amount of small-scale power. We choose several popular models of inflation and work out the ramifications for galaxy central densities. For each model, we calculate its COBE-normalized power spectrum and deduce the implied halo densities using a semi-analytic method calibrated against N-body simulations. We compare our predictions to a sample of dark matter-dominated galaxies using a non-parametric measure of the density. While standard n=1, LCDM halos are overdense by a factor of 6, several of our example inflation+CDM models predict halo densities well within the range preferred by observations. We also show how the presence of massive (0.5 eV) neutrinos may help to alleviate the central density problem even with n=1. We conclude that galaxy central densities may not be as problematic for the CDM paradigm as is sometimes assumed: rather than telling us something about the nature of the dark matter, galaxy rotation curves may be telling us something about inflation and/or neutrinos. An important test of this idea will be an eventual consensus on the value of sigma_8, the rms overdensity on the scale 8 h^-1 Mpc. Our successful models have values of sigma_8 approximately 0.75, which is within the range of recent determinations. Finally, models with n>1 (or sigma_8 > 1) are highly disfavored.Comment: 13 pages, 6 figures. Minor changes made to reflect referee's Comments, error in Eq. (18) corrected, references updated and corrected, conclusions unchanged. Version accepted for publication in Phys. Rev. D, scheduled for 15 August 200

Temporal, spatial, and structural patterns of adult trembling aspen and white spruce mortality in Quebec's boreal forest

Temporal, spatial, and structural patterns of adult trembling aspen (Populus tremuloides Michx.) and white spruce (Picea glauca (Moench) Voss) mortality were studied in intact 150-year-old stands in the southwestern boreal forest of Quebec. For both species, mortality decreases (number of dead trees/total number of trees) with distance from the lake edge until 100-150 m, from which point it slightly increases. Strong peaks in mortality were found for 40- to 60-year-old aspen mainly between 1974 and 1992. Such mortality in relatively young aspen is likely related to competition for light from the dominant canopy trees. Also, the recruitment of this young aspen cohort is presumably the result of a stand breakup that occurred when the initial aspen-dominated stand was between 90 and 110 years old. For spruce, strong peaks in mortality were found in 110- to 150-year-old trees and they occurred mainly after 1980. No clear explanation could be found for these peaks, but we suggest that they may be related to senescence or weakening of the trees following the last spruce budworm outbreak. Suppressed and codominant aspen had a much higher mortality ratio than spruce in the same height class, while more surprisingly, no difference in mortality rate was found between dominant trees of the two species. Most spruce trees were found as standing dead, which leads us to reject the hypothesis that windthrow is an important cause of mortality for spruce in our forests

Mass spectrometry analysis of metals, other elements and lipids in urine samples of Fabry disease patients

Fabry disease is an X-linked lysosomal storage disorder caused by deficiency of alpha-galactosidase A leading to accumulation of globotriaosylceramide in tissues and biological fluids of affected patients. Mass spectrometry is a powerful tool to quantify components of interest in biological fluids. Our study had four objectives: (1) to devise an ICP-MS methodology for quantitative determination of metal and other element concentrations in urine specimens of Fabry patients; (2) to analyze urinary Gb(3)/creatinine and lyso-Gb(3)/creatinine in these patients; (3) to evaluate correlations between urinary lipid concentrations versus metals and other elements in Fabry patients and healthy controls; (4) to evaluate which metals and other elements discriminate groups of patients and controls according to gender and treatment. We found that the excretion of barium was elevated in Fabry females and calcium and strontium levels were lower in Fabry males compared to controls. Preliminary results for treated and untreated Fabry disease patients indicate that ERT seems to have little effect on urine elements analyzed. Statistically significant correlations were established between urinary lyso-Gb(3)/creatinine. Gb(3)/creatinine and levels of magnesium, copper, mercury, nickel, lead, barium and calcium, whereas no significant correlations were found for the other 15 elements examined. Our results indicate that further studies are warranted in larger cohorts of Fabry disease patients for the investigation of possible roles of metals and other elements. (C) 2011 Elsevier B.V. All rights reserved

Work Fatigue Profiles: Nature, Implications, and Associations With Psychological Empowerment

International audienc

A multilevel perspective on the role of job demands, job resources, and need satisfaction for employees' outcomes

International audienceThis study investigates the mediator role of psychological need satisfaction for the effects of job demands and resources on turnover intentions, psychological distress, and work-to-family conflict, simultaneously at the employee and work unit levels. In doing so, we consider how need satisfaction, when considered at the work unit level, creates a context likely to play an additional role in the prediction of these outcomes. These questions were investigated using a combination of doubly latent multilevel confirmatory factor analyses and structural equation models applied to responses provided by a large sample (N = 5,716 employees nested within 50 work units) of Canadian Armed Forces/Department of National Defence personnel. The results supported the idea that work environment effects on the outcomes considered in this study were mediated by psychological need satisfaction at the individual and work unit levels and demonstrated that these associations were driven by global work environment perceptions and global need satisfaction. Furthermore, need satisfaction was found to create a context, at the work unit level, leading employees working in units including more highly satisfied co-workers to present higher levels of turnover intentions but lower levels of work-to-family conflict than would be expected based on their individual levels of need satisfaction

European Union Import Quotas on Chinese Textile and Clothing Exports in 2005: A Panic-Driven Commission or Rational Explanations?

import quotas, European Union, textiles, clothing, China, D72, F14, F53,